Diabetes Drug May Boost Ovarian Ca Survival

The first-line diabetes drug metformin may have a place in ovarian cancer treatment, researchers found.

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The first-line diabetes drug metformin may have a role in ovarian cancer treatment.

Point out that the study suggests that metformin should be evaluated in prospective trials for treating ovarian cancer given its association association with improved survival.

The first-line diabetes drug metformin may have a role in ovarian cancer treatment, researchers found.

In a retrospective, case-control study, women who'd been taking metformin during their ovarian cancer treatment -- primarily for type 2 diabetes -- had significantly better survival than cancer patients not on the drug (73% versus 44%, P=0.0002), reported Viji Shridhar, PhD, of the Mayo Clinic in Rochester, Minn., and colleagues online in Cancer.

"Although causation could not be assessed [in a case-control study], we observed that receipt of metformin was associated with significantly better survival in ovarian cancer," they wrote. "Metformin is worthy of clinical trials in ovarian cancer."

Most of the currently available therapies in up-front and recurrent ovarian cancer have limited efficacy, the researchers said, yet it's prohibitively expensive to discover and develop new drugs.

Instead, some researchers are turning to drug repositioning, in which existing drugs are used to treat new diseases.

Metformin, a first-line agent in type 2 diabetes, has previously shown anti-cancer effects in ovarian cancer, both in vitro and in vivo, and similar observations have been made for neoplasms in the prostate, colon, pancreas, and brain.

There is also a multi-center, phase III, randomized trial testing metformin in breast cancer, the researchers said.

Because only small studies have looked at outcomes for ovarian cancer patients treated with metformin, Shridhar's group conducted a retrospective case-control study of ovarian cancer patients who were treated at the Mayo Clinic between 1995 and 2010.

A total of 72 of these women had been taking metformin for type 2 diabetes during their ovarian cancer treatment, and they were matched with 143 controls who didn't have diabetes and weren't taking metformin.

They also assessed a subset of 61 women who'd had epithelial ovarian cancer, and compared them with 178 nondiabetic controls with the same disease.

The researchers also included a diabetic control group of 103 patients who had both diabetes and epithelial ovarian cancer and were taking insulin or other diabetes drugs instead of metformin.

Overall, the mean duration of metformin intake was 2.3 years, given at doses ranging from 500 mg twice a day to 1 gram twice a day.

In the analysis of 72 cases and 143 controls, Shridhar and colleagues found that cancer cases taking metformin had significantly better 5-year disease-specific survival than controls (73% versus 44%, P=0.0002).

In the analysis of cases and controls with epithelial ovarian cancer, those taking metformin also had significantly better 5-year survival (67% versus 47%, P=0.006).

And when comparing the epithelial cohort taking metformin to diabetic controls with epithelial disease, the researchers again found significantly better survival for those on metformin (67% versus 40%, P=0.003).

The study was limited by its retrospective nature, its small sample size, and a lack of information on patient intake of metformin before their cancer diagnosis.

Still, the authors concluded that metformin appears to be associated with better survival in ovarian cancer patients, and that the drug should be evaluated in prospective trials for treating this disease.

The study was supported by grants from the Fred C. and Katherine B. Andersen Foundation and NIH.

The researchers reported no conflicts of interest.

Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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